From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 98250C43387 for ; Fri, 21 Dec 2018 15:21:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 659792192C for ; Fri, 21 Dec 2018 15:21:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1545405708; bh=CdVcXUPxEenhQazRju8vpgsrfaPPvQHLLa9CCNypoX8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:In-Reply-To: References:List-ID:From; b=qq2u2Ty3flsdnVd2Ipdeq+cMXu7jbjOWK+7IDkHSLxa1qlg+6iutIAnFwZLMXHMyJ qlLjbMY2UrrEFPITL8akSwvtK+/fGQp2qvrWP60LXQYPlYfooQiUFGUQS9E+zbNFe/ JOvIEP6if8OmFm9el1bnBUOaBZ5vXQtkfGbgG9AE= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2404220AbeLUPVr (ORCPT ); Fri, 21 Dec 2018 10:21:47 -0500 Received: from mail.kernel.org ([198.145.29.99]:57304 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2404137AbeLUPVp (ORCPT ); Fri, 21 Dec 2018 10:21:45 -0500 Received: from localhost.localdomain (c-98-220-238-81.hsd1.il.comcast.net [98.220.238.81]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 6EA0121927; Fri, 21 Dec 2018 15:21:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1545405704; bh=CdVcXUPxEenhQazRju8vpgsrfaPPvQHLLa9CCNypoX8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:In-Reply-To: References:From; b=eekWvfGe8rMbuy/F3rxxfWXiQGgwcSWDKC7sJpgI6m42fRhsdSYMGl5U1VyaGPG4v teddTfsO7L/E898+kWRrBjtfabYQ3Hko4wKKlzDnDpB3dGLqRiuHNsTy7/90qzGE3u l9S6KapBM6G539JoJApxFNP0pC6kFGUxK9R1zSOA= From: Tom Zanussi To: linux-kernel@vger.kernel.org, linux-rt-users@vger.kernel.org Cc: rostedt@goodmis.org, tglx@linutronix.de, C.Emde@osadl.org, jkacur@redhat.com, bigeasy@linutronix.de, daniel.wagner@siemens.com, julia@ni.com Subject: [PATCH RT 7/9] pinctrl: bcm2835: Use raw spinlock for RT compatibility Date: Fri, 21 Dec 2018 09:21:19 -0600 Message-Id: <1b44e8b14448276fcc768b7da4937de95973e94c.1545347029.git.tom.zanussi@linux.intel.com> X-Mailer: git-send-email 2.14.1 In-Reply-To: References: In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org v3.18.129-rt111 rt-stable review patch. If anyone has any objections, please let me know. ------------------ From: Lukas Wunner [Upstream rt-devel commit 55016fa934eb0d4e037beef2b2f503012dfebeac] [Upstream commit 71dfaa749f2f7c1722ebf6716d3f797a04528cba] The BCM2835 pinctrl driver acquires a spinlock in its ->irq_enable, ->irq_disable and ->irq_set_type callbacks. Spinlocks become sleeping locks with CONFIG_PREEMPT_RT_FULL=y, therefore invocation of one of the callbacks in atomic context may cause a hard lockup if at least two GPIO pins in the same bank are used as interrupts. The issue doesn't occur with just a single interrupt pin per bank because the lock is never contended. I'm experiencing such lockups with GPIO 8 and 28 used as level-triggered interrupts, i.e. with ->irq_disable being invoked on reception of every IRQ. The critical section protected by the spinlock is very small (one bitop and one RMW of an MMIO register), hence converting to a raw spinlock seems a better trade-off than converting the driver to threaded IRQ handling (which would increase latency to handle an interrupt). Cc: Mathias Duckeck Signed-off-by: Lukas Wunner Acked-by: Julia Cartwright Signed-off-by: Linus Walleij Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Tom Zanussi Conflicts: drivers/pinctrl/bcm/pinctrl-bcm2835.c --- drivers/pinctrl/pinctrl-bcm2835.c | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-) diff --git a/drivers/pinctrl/pinctrl-bcm2835.c b/drivers/pinctrl/pinctrl-bcm2835.c index eabba02f71f9..9a975a12b8e3 100644 --- a/drivers/pinctrl/pinctrl-bcm2835.c +++ b/drivers/pinctrl/pinctrl-bcm2835.c @@ -106,7 +106,7 @@ struct bcm2835_pinctrl { struct pinctrl_gpio_range gpio_range; struct bcm2835_gpio_irqdata irq_data[BCM2835_NUM_BANKS]; - spinlock_t irq_lock[BCM2835_NUM_BANKS]; + raw_spinlock_t irq_lock[BCM2835_NUM_BANKS]; }; static struct lock_class_key gpio_lock_class; @@ -465,10 +465,10 @@ static void bcm2835_gpio_irq_enable(struct irq_data *data) unsigned bank = GPIO_REG_OFFSET(gpio); unsigned long flags; - spin_lock_irqsave(&pc->irq_lock[bank], flags); + raw_spin_lock_irqsave(&pc->irq_lock[bank], flags); set_bit(offset, &pc->enabled_irq_map[bank]); bcm2835_gpio_irq_config(pc, gpio, true); - spin_unlock_irqrestore(&pc->irq_lock[bank], flags); + raw_spin_unlock_irqrestore(&pc->irq_lock[bank], flags); } static void bcm2835_gpio_irq_disable(struct irq_data *data) @@ -479,10 +479,10 @@ static void bcm2835_gpio_irq_disable(struct irq_data *data) unsigned bank = GPIO_REG_OFFSET(gpio); unsigned long flags; - spin_lock_irqsave(&pc->irq_lock[bank], flags); + raw_spin_lock_irqsave(&pc->irq_lock[bank], flags); bcm2835_gpio_irq_config(pc, gpio, false); clear_bit(offset, &pc->enabled_irq_map[bank]); - spin_unlock_irqrestore(&pc->irq_lock[bank], flags); + raw_spin_unlock_irqrestore(&pc->irq_lock[bank], flags); } static int __bcm2835_gpio_irq_set_type_disabled(struct bcm2835_pinctrl *pc, @@ -584,14 +584,14 @@ static int bcm2835_gpio_irq_set_type(struct irq_data *data, unsigned int type) unsigned long flags; int ret; - spin_lock_irqsave(&pc->irq_lock[bank], flags); + raw_spin_lock_irqsave(&pc->irq_lock[bank], flags); if (test_bit(offset, &pc->enabled_irq_map[bank])) ret = __bcm2835_gpio_irq_set_type_enabled(pc, gpio, type); else ret = __bcm2835_gpio_irq_set_type_disabled(pc, gpio, type); - spin_unlock_irqrestore(&pc->irq_lock[bank], flags); + raw_spin_unlock_irqrestore(&pc->irq_lock[bank], flags); return ret; } @@ -1004,7 +1004,7 @@ static int bcm2835_pinctrl_probe(struct platform_device *pdev) pc->irq[i] = irq_of_parse_and_map(np, i); pc->irq_data[i].pc = pc; pc->irq_data[i].bank = i; - spin_lock_init(&pc->irq_lock[i]); + raw_spin_lock_init(&pc->irq_lock[i]); len = strlen(dev_name(pc->dev)) + 16; name = devm_kzalloc(pc->dev, len, GFP_KERNEL); -- 2.14.1